Question

Why is Q factor important?

Answer 1

Q Factor or Quality Factor

1. The quality factor of a resonant circuit describes the quality or performance of the resonant circuit.
2. A high value of Q means a narrow bandwidth which is desirable in many applications.
3. In other words, Q is the ratio of reactive power to the average power in the circuit reactance and resistance per cycle.

$Q=reactivepower/averagepower$

When dealing with an RF tuned circuit there are many factors why Q is important some of them are listed below:

1. Bandwidth: When the Q factor or quality factor is increased then the bandwidth of the tuned circuit is decreased. When bandwidth is decreased then losses through the circuit are decreased, and the tuned circuit becomes shaper, and now more energy is stored in the circuit.
2. Spurious Signals: Tuned circuits are used to remove spurious signals. If the Q value is higher, then the circuit will be better to remove the spurious signals.
3. Oscillator Phase Noise: All the oscillators generate phase noise which is the shift from the phase of the signal. This is expected as a noise that spreads out from the carrier. This noise is unwanted and needs to be reduced. The oscillator can be modified to reduce this noise in several ways, the main of them is by increasing the value of quality factor Q of the oscillator tuned circuit.

Hence, the Q factor is important.